Compressor

ABSTRACT

Oil sucked by an oil pump and supplied to an opening at an eccentric shaft flows on the top end face of the eccentric shaft to the outer periphery thereof, and splashes from an edge in substantially a radial direction onto the sliding portions of a cylinder and a piston. Thus, the oil can cool the cylinder and piston, form oil film on the sliding portions of the cylinder and piston, restrain metallic contact between the sliding portions, and prevent abrasion between the sliding portions and increasing input into the compressor.

TECHNICAL FIELD

The present invention relates to a compressor used for refrigeratingcycle such as a fridge freezer.

BACKGROUND ART

A conventional example of this kind of compressor includes a mechanismfor supplying oil to the cylinder thereof (see Patent Document 1, forexample).

Hereinafter, the conventional compressor is described with reference tothe accompanying drawings.

FIG. 6 is a longitudinal sectional view of the conventional compressorof Patent Document 1 as seen from a side thereof. FIG. 7 is across-sectional view of the conventional compressor. FIG. 8 is alongitudinal sectional view of the conventional compressor as seen fromthe front thereof. FIG. 9 is a sectional view of an essential part of asuction muffler of the conventional compressor.

With reference to FIGS. 6, 7, 8, and 9, hermetic container 1 has oil 2stored at the bottom thereof, and has refrigerant gas 3 filling thespace thereof.

Electrically-driven element 4 includes stator 5 and rotor 6. Compressingelement 7 includes the following components: crankshaft 10 havingeccentric shaft 8 and main shaft 9; cylinder block 13 having cylinder 11and main bearing 12; piston 14; and connecting rod 15. Rotor 6 is fittedonto crankshaft 10. Crankshaft 10 includes oil pump 17, and rotates inmain bearing 12. At least the bottom end of oil pump 17 is immersed inoil 2. Oil pump 17 has opening 16 for splashing oil 2 from the top endface of eccentric shaft 8 into hermetic container 1.

Piston 14 is inserted into substantially columnar cylinder 11 so as tobe reciprocatingly slidable therein. Piston 14 is coupled to eccentricshaft 8 via connecting rod 15. Valve plate 18 that seals the opening endface of cylinder 11 includes suction port 19 to be communicated tocylinder 11 by the opening/closing operation of a suction valve (notshown).

Cylinder head 21 forming communication channel 20 is fixed on theopposite side of cylinder 11 via valve plate 18.

Suction muffler 25 is made up of a channel for sucking refrigerant gas 3opened to hermetic container 1, i.e. tail pipe 26, and sound-absorbingspace 27. The suction muffler is coupled to one end of communicationchannel 20.

Oil reservoir 28 is provided at the opening of tail pipe 26 in hermeticcontainer 1 in a concave shape.

Hereinafter, an operation of the compressor structured as above isdescribed.

The rotation of crankshaft 10 caused by electrically-driven element 4 istransferred to connecting rod 15, thereby reciprocating piston 14. Thereciprocating movement releases refrigerant gas 3 flowing from anexternal cooling circuit (not shown) once into hermetic container 1, andinto sound-absorbing space 27 in suction muffler 25 via tail pipe 26.Thereafter, refrigerant gas 3 is intermittently sucked into cylinder 11via communication channel 20, and suction port 19 of valve plate 18.Refrigerant gas 3 sucked into cylinder 11 is compressed by piston 14 anddischarged to the external cooling circuit (not shown) again.

When crankshaft 10 is rotated by electrically-driven element 4, oil 2stored at the inner bottom of hermetic container 1 is pumped up incrankshaft 10 by oil pump 17. After lubricating the sliding portions ofmain shaft 9 and eccentric shaft 8, oil 2 splashes from opening 16 ofoil pump 17 in eccentric shaft 8 into hermetic container 1 and ontocylinder 11. A part of the oil accumulates in oil reservoir 28. Thetrajectory of oil 2 splashing from opening 16 of oil pump 17 intohermetic container 1 is shown by the arrows in FIG. 6.

The rotation of eccentric shaft 8 causes connecting rod 15 toreciprocate piston 14 in cylinder 11. Thereby, the suction, compression,and discharge strokes are sequentially repeated. In the suction strokeof piston 14, refrigerant gas 3 filling the space of hermetic container1 is sucked from the tip of tail pipe 26.

At that time, oil 2 in oil reservoir 28 is sucked from the tip of tailpipe 26 together with refrigerant gas 3. The oil is supplied intocylinder 11 via suction muffler 25, communication channel 20, andsuction port 19 of valve plate 18, and lubricates the sliding portionsof piston 14 and cylinder 11.

However, in the conventional structure, the direction in which oil 2discharged from opening 16 of oil pump 17 splashes is unstable becausethe direction varies with the rotation speed of crankshaft 10, theviscosity of oil 2 or the like. For this reason, oil 2 does not splashonto cylinder 11 and does not lubricate the sliding portions of cylinder11 and piston 14. This phenomenon may cause metallic contact andabrasion between the portions.

Because the direction in which oil 2 from opening 16 of oil pump 17splashes is unstable depending on the changes in operating conditions,oil 2 splashing in hermetic container 1 sometimes does not accumulate inoil reservoir 28. In such a case, oil 2 is not supplied from oilreservoir 28 into cylinder 11. This can degrade the sealability betweenvalve plate 18 and the suction valve, thus freezing capability andefficiency may be degraded.

-   [Patent Document 1] Japanese Patent Unexamined Publication No.    H06-294380

SUMMARY OF THE INVENTION

A compressor includes a hermetic container that stores oil therein andaccommodates a compressing element for compressing a refrigerant gas.The compressing element includes the following components: a crankshaftthat has an eccentric shaft and a main shaft, and an oil pump having anopening on a top end face of the eccentric shaft; a cylinder block thathas a cylinder and a main bearing; a piston that reciprocates in thecylinder; and a suction muffler that forms a sound-absorbing space incommunication with the cylinder. The eccentric shaft has an edge thatmakes an acute angle with the top end face, along the outer periphery ofthe top end of the eccentric shaft.

The oil sucked by the oil pump and supplied to the opening of theeccentric shaft flows on the top end face of the eccentric shaft to theouter periphery thereof, and splashes from the edge having the acuteangle at the end of the eccentric shaft in substantially a radialdirection. Thus, the oil splashes linearly onto the sliding portions ofthe cylinder and piston, cools the cylinder and piston, and forms oilfilm on the sliding portions of the cylinder and piston, under hardlyany influence of the operating conditions of the compressor. As aresult, the oil can restrain metallic contact between the slidingportions and prevent abrasion between the sliding portions andincreasing input into the compressor. Thus, a compressor having highefficiency and high reliability can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional view of a compressor in accordancewith an exemplary embodiment of the present invention as seen from aside thereof.

FIG. 2 is a cross-sectional view of the compressor in accordance withthe exemplary embodiment.

FIG. 3 is a sectional view of an essential part of a crankshaft inaccordance with the exemplary embodiment.

FIG. 4 is a sectional view of an essential part of a suction muffler inaccordance with the exemplary embodiment.

FIG. 5 is a sectional view of the suction muffler taken on line A-A ofFIG. 4.

FIG. 6 is a longitudinal sectional view of a conventional compressor asseen from a side thereof.

FIG. 7 is a cross-sectional view of the conventional compressor.

FIG. 8 is a longitudinal sectional view of the conventional compressoras seen from the front thereof.

FIG. 9 is a sectional view of an essential part of a suction muffler ofthe conventional compressor.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Hereinafter, a compressor in accordance with the exemplary embodiment ofthe present invention is described with reference to the accompanyingdrawings.

Exemplary Embodiment

FIG. 1 is a longitudinal sectional view of a compressor in accordancewith the exemplary embodiment of the present invention as seen from aside thereof. FIG. 2 is a cross-sectional view of the compressor inaccordance with the exemplary embodiment. FIG. 3 is a sectional view ofan essential part of a crankshaft in accordance with the exemplaryembodiment. FIG. 4 is a sectional view of an essential part of a suctionmuffler in accordance with the exemplary embodiment. FIG. 5 is asectional view of the suction muffler taken on line A-A of FIG. 4.

With reference to FIGS. 1, 2, 3, 4, and 5, hermetic container 101 hasoil 102 stored therein and is filled with refrigerant gas 103.

Electrically-driven element 110 includes stator 111 and rotor 112.Compressing element 113 includes crankshaft 116 driven byelectrically-driven element 110, cylinder block 119 having cylinder 117and main bearing 118, piston 120, and connecting rod 121, to form areciprocating compressor mechanism.

Piston 120 is inserted into cylinder 117 so as to be reciprocatinglyslidable therein. Piston 120 is coupled to eccentric shaft 124 viaconnecting rod 121.

Crankshaft 116 includes eccentric shaft 124 and main shaft 125, androtates in main bearing 118 with rotor 112 fitted onto the crankshaft.Oil pump 126 provided through crankshaft 116 includes oil channel 128 inmain shaft 125, and rotates with at least the bottom end thereofimmersed in oil 102.

Chamfer 132 is provided along opening 131 of oil pump 126 positioned attop end face 133 of eccentric shaft 124.

Eccentric shaft 124 includes edge 130 that makes an acute angle with topend face 133, along the outer periphery of the top end of the eccentricshaft. External diameter E of edge 130 is dimensioned smaller than theexternal diameter of eccentric shaft 124 that slides with connecting rod121. The acute angle that edge 130 makes with top end face 133 is shownas angle a in FIG. 3.

Valve plate 135 that seals the opening end face of cylinder 117 includessuction port 136 to be communicated to cylinder 117 by theopening/closing operation of a suction valve (not shown).

Cylinder head 138 that forms communication channel 137 is fixed on theopposite side of cylinder 117 via valve plate 135.

Suction muffler 140 is integrally formed with cylinder block 119.Suction muffler 140 includes top section 142 curving outwardly ofsuction muffler 140 having a convex shape with a curvature exceeding 0,oil-suction hole 143 provided at top section 142, sound-absorbing space144, and tail pipe 145. Suction muffler 140 communicates withsound-absorbing space 144 and cylinder 117 via communication channel 137and suction port 136. Tail pipe 145 of suction muffler 140 is opened tohermetic container 101 at one end, and to sound-absorbing space 144 atthe other end. Thus, the tail pipe forms a suction channel forintroducing refrigerant gas 103 in hermetic container 101 intosound-absorbing space 144.

Oil-suction hole 143 is a through-hole that is provided at substantiallythe crest of top section 142 and allows the space in hermetic container101 to communicate with sound-absorbing space 144 in suction muffler140.

An operation of the compressor structured as above is describedhereinafter.

The rotation of crankshaft 116 is transferred to connecting rod 121,thereby reciprocating piston 120. The reciprocating movement of piston120 releases refrigerant gas 103 introduced from an external coolingcircuit (not shown) once into hermetic container 101, and intosound-absorbing space 144 in suction muffler 140 via tail pipe 145.Thereafter, refrigerant gas 103 is intermittently sucked into cylinder117 via communication channel 137 and suction port 136 of valve plate135. Refrigerant gas 103 sucked into cylinder 117 is compressed bypiston 120 and discharged to the external cooling circuit (not shown)again.

When crankshaft 116 is rotated by electrically-driven element 110, oil102 stored at the inner bottom of hermetic container 101 is pumped up incrankshaft 116 by oil pump 126. Oil 102 goes through oil channel 128 andreaches opening 131 formed through top end face 133 of oil pump 126.

When oil 102 reaches opening 131, oil 102 is pushed out not directlyabove but in an oblique direction along chamfer 132. Substantiallyentire oil 102 flows to the outer periphery along top end face 133 ofeccentric shaft 124 by centrifugal force. Thereafter, the oil splashesfrom edge 130 having the acute angle at the end in substantially aradial direction. The trajectory of oil 102 splashing from edge 130 intohermetic container 101 is shown by the arrows in FIGS. 1 and 3.

As a result, substantially entire oil 102 that has reached opening 131of oil pump 126 splashes linearly onto the sliding portions of cylinder117 and piston 120, under hardly any influence of the operatingconditions, such as the rotation speed of crankshaft 116 and theviscosity of oil 102. Thus, cylinder 117, piston 120, and othercomponents can sufficiently be cooled, and oil film can be formed on thesliding portions of cylinder 117 and piston 120. Thus, the oil canrestrain metallic contact between the sliding portions, and preventabrasion between the sliding portions and increasing input into thecompressor. Thus, a compressor having high efficiency and highreliability can be provided.

In the above structure, eccentric shaft 124 includes edge 130 that makesan acute angle with top end face 133, along the outer periphery of theeccentric shaft. If the angle that edge 130 and top end face 133 makewith each other is a right angle or an obtuse angle instead of an acuteangle, oil 102 introduced to edge 130 splashes not in a radial directionbut obliquely downward with respect to the horizontal direction. Thereason is inferred as follows. If the angle that edge 130 and top endface 133 make with each other is a right angle or an obtuse angleinstead of an acute angle, the splashing force in a radial direction isinhibited by the surface tension of oil 102 or the like.

Further, when hermetic container 101 is at a low temperature and oil 102has a high viscosity, or when the compressor is operated at a lowrotation speed, e.g. 50 Hz, and oil pump 126 has a small pumping force,upward splash of oil 102 is difficult.

In contrast, when hermetic container 101 is at a high temperature andoil 102 has a low viscosity, or when the compressor is operated at ahigh rotation speed, e.g. 60 Hz, and oil pump 126 has a large pumpingforce, oil 102 tends to splash high. However, the following phenomenaare confirmed in the above structure. Oil 102 splashes from edge 130having an acute angle in substantially a radial direction linearly ontothe sliding portions of cylinder 117 and piston 120, in spite ofoperating conditions, such as the viscosity and the rotation speed ofcrankshaft 116. The position onto which the oil splashes hassubstantially no change.

Further, chamfer 132 is provided along opening 131 of oil pump 126. Inthis structure, oil 102 having reached opening 131 is pushed out notdirectly above but in an oblique direction, as compared with the case ofwithout chamfer 132. Thus, substantially entire oil 102 does not splashupwardly, and flows to the outer periphery along top end face 133 ofeccentric shaft 124 by centrifugal force. This special advantage is alsoconfirmed.

However, the following advantage is also confirmed. Even in thestructure without chamfer 132, among oil 102 reached opening 131, oil102 flowing to the outer periphery along top end face 133 of eccentricshaft 124 splashes from edge 130 in substantially a radial directionlinearly onto the sliding portions of cylinder 117 and piston 120.

Top section 142 of suction muffler 140 is disposed at a position whereoil 102 splashing from edge 130 in substantially a radial direction hitsdirectly. The top section also includes oil-suction hole 143. With thisstructure, oil 102 continuously splashes onto top section 142 and formsoil film on the surface of top section 142, during the operation of thecompressor.

Further, top section 142 of suction muffler 140 forms a convex shapehaving a curvature exceeding 0. With this structure, oil 102 splashingonto and adhering to the surface of top section 142 does not remain onthe surface of top section 142. The oil is spread thin on top section142 by the surface tension of the oil and can form oil film. Then,oil-suction hole 143 can suck a fixed amount of oil 102 according to theinner peripheral length of the hole from the oil film spread thin atsubstantially a fixed thickness, using the negative pressure inside ofsuction muffler 140.

The suction of oil 102 in the oil film near oil-suction hole 143 intosuction muffler 140 through oil-suction hole 143 allows stablelubrication to the inside of cylinder 117 via sound-absorbing space 144,communication channel 137, and suction port 136 through valve plate 135.

As a result, entry of a large amount of oil 102 into cylinder 117 can beprevented, and thus piston 120 does not compress refrigerant gas 103containing a large amount of oil 102. This structure can preventunnecessary increase in the load imposed on piston 120 and increasinginput into the compressor and improve the sealability between valveplate 135 and the suction valve. Thus, efficiency can be improved.

Further, edge 130 is smaller than the external diameter of eccentricshaft 124 that slides with connecting rod 121. For this reason, whenconnecting rod 121 is inserted into eccentric shaft 124 during assemblyof the compressor, contact of the sliding surface of the inner peripheryof connecting rod 121 with edge 130 of eccentric shaft 124 can beprevented. This structure can prevent the sliding surface of connectingrod 121 from being damaged by edge 130 of eccentric shaft 124, therebyimproving the quality and reliability.

For these reasons, a compressor having high reliability, efficiency, andquality can be provided.

In the description of the exemplary embodiment of the present invention,edge 130 is integrally formed with crankshaft 116. However, an edge anda crankshaft separately formed into the same shape as theintegrally-formed component can also give the same advantage as theexemplary embodiment of the present invention.

Further, a slight chamfer can be provided along edge 130 to prevent thedamage to the sliding surface of connecting rod 121 in case that edge130 makes contact with connecting rod 121 during assembly thereof. Alsowith this structure, the oil splashing effect can be maintained.

INDUSTRIAL APPLICABILITY

As described above, a compressor of the present invention has highreliability and efficiency, and thus can be used in any applicationusing a refrigerating cycle, such as a domestic refrigerator, adehumidifier, a showcase, and an automatic vending machine.

REFERENCE MARKS IN THE DRAWINGS

-   101 Hermetic container-   102 Oil-   103 Refrigerant gas-   113 Compressing element-   116 Crankshaft-   117 Cylinder-   118 Main bearing-   119 Cylinder block-   120 Piston-   121 Connecting rod-   124 Eccentric shaft-   125 Main shaft-   126 Oil pump-   130 Edge-   131 Opening-   132 Chamfer-   133 Top end face-   140 Suction muffler-   142 Top section-   143 Oil-suction hole-   144 Sound-absorbing space

1. A compressor comprising: a hermetic container that stores oil thereinand accommodates a compressing element for compressing a refrigerantgas, the compressing element including: a crankshaft including aneccentric shaft and a main shaft, and including an oil pump having anopening on a top end face of the eccentric shaft; a cylinder blockincluding a cylinder and a main bearing; a piston inserted into thecylinder and reciprocating; and a suction muffler having asound-absorbing space formed therein, the sound-absorbing space being incommunication with the cylinder; wherein the eccentric shaft has an edgemaking an acute angle with the top end face, along an outer periphery ofa top face of the eccentric shaft.
 2. The compressor of claim 1, whereina chamfer is provided along the opening of the top end face of the oilpump on.
 3. The compressor of claim 1, further including a connectingrod for coupling the eccentric shaft to the piston, wherein an externaldiameter of the edge is dimensioned smaller than that of the eccentricshaft that slides with the connecting rod.
 4. The compressor of claim 1,wherein the suction muffler includes an oil-suction hole at a positionwhere the oil splashing from the edge hits directly.
 5. The compressorof claim 4, wherein a top section of the suction muffler forms a convexhaving a curvature exceeding 0 and includes the oil-suction hole near acrest of the top section.